Coating photographic material



3,018,178 COATING PHOTOGRAPHIC MATERIAL Benjamin B. Harriman, Rochester, N.Y. No Drawing. Filed Oct. 29, 1956, Ser. No. 618,709

3 Claims. (Cl. 96-94) This invention relates to photographic film, and more particularly to layers of such film, containing as a spreading agent, a condensation product of an amine with a fatty acid, and to photographic elements containing said spreading agent.

Conventional photographic film is constructed with a base which may be a flexible plastic such as a cellulose ester, i.e., cellulose acetate or ethylene glycol-terephthalate polyester, or may be a rigid support such as glass. Next, a bonding or subbing layer is applied to the base or support in order to anchor subsequently coated layers of a photographic colloid such as gelatin, P.V.A., or a light sensitive gela-tino silver halide to the support. This so-called subbing layer serves to enmesh the colloid layer with the support. However, photographic colloids and emulsion layers cannot be coated uniformly unless they contain a surfactant whose function is to provide uniform spreading and wetting and, at the same time, prevent the formation of foam, bubbles and repellent spots.

Often multiple coatings of gelatin solutions are applied on a single support. For example, three separate gelatino silver halide emulsion layers are successively coated in making color films. Similarly, many photographic films carry a thin gelatin layer over the surface of the emulsion to protect it from abrasions and pressure marks. The Wetting and spreading problems in applying a gelatin or other colloid layer over a gelatin layer are quite different from those encountered when a gelatin layer is applied directly on the film support. This is particularly true if the undercoating is a freshly coated, wet, chilled layer.

For many years, saponin has been widely used as a wetting agent in the manufacture of photographic films, being more universally applicable than any other surfactant. However, it has several disadvantages, chief among them being its foaming characteristics. In addition, it is a naturally occurring substance obtained by the extraction of the bark of a South American tree and, as such, shows consider-able variation in quality from batch to batch.

The more recent trend in surfactants for photographic use has been toward the synthetic products. Numerous patents have been issued covering the use of such compounds not only as spreading agents but also to impart antistatic properties, increase the solubility of color formers, facilitate the penetration of processing solutions, reduce the danger of water spots, eliminate air bubbles when a warm gelatin solution is coated over a chilled emulsion layer, accelerate development, prevent antihalation dyes from staining the support, etc. Most of these synthetic surfactants are very specific in their action, and one that may be good for one particular emulsion or gelatin formula may not be efiective at all in helping to spread or prevent repellent spots in another formulation. For this reason, most of the synthetic surfactants have a limited field of use. This partly explains the relatively large number of proposals on the use of surfactants of different types in photographic films.

One of the most diflicult coatings to apply uniformly is colloidal silver suspended in a relatively dilute gelatin solution. Solutions of this type are frequently applied directly to a film support to act as antihalation layers. To obtain uniform dispersion of the colloidal silver and to coat it upon the support while, at the same time, avoiding foam and repellent spots, has been next to impossible.

3,618,178 Patented Jan. 23, 1 962 The purpose of the present invention is to provide a means for applying such difiicultly coatable solutions.

A further object of this invention is to permit the coating of these solutions with freedom from foam, repellent spots and other coating defects.

Another object of the invention is to provide a coating solution which is stable and can 'be held in a melted condition at an elevated temperature without settling.

A still further object of the invention is to coat a photographic gelatin layer over which a second gelatin layer can be coated without difficulty, either in a separate coating machine pass or in the same pass over the wet, chilled undercoating.

The success of my invention is predicated upon the use, as a surfactant in the coating formulations, of water soluble alkylol amine-fatty acid condensates which are primarily hydroxy alkyl acylamides.

It is recognized that in condensing alkylol amines with fatty acids, particularly those of high molecular weight, the condensation may lead to salts of the amines and fatty acids, and the esters, amides, or ester amides thereof. It has been my finding that, unless the condensation product employed is substantially free from the salts, esters, and ester amides, unsatisfactory results ensue. Thus, I have experimented with the product sold under the trade name Clavodene which is sold by the Dexter Chemical Company and which is prepared by condensing diethanolamine with mixed fatty acids but in which the reaction conditions are such that a substantial quantity of the diethanol ammonium salt of the mixed fatty acids is formed. The resulting product is not entirely water soluble in neutral or acid solutions and exhibits inferior properties when compared to those condensatcs which are essentially the amides. Typical of such products is that prepared from 1 mole of coconut fatty acid and more than 1 mole of diethanol amine and sold under the trade name Emcol 5100 by the Emulsol Corp.

The alkylol amine-fatty acid condensates which are primarily the amides are produced according to the method described by W. Kritchevsky in US. Patent 2,089,212 in which a higher fatty acid is condensed with more than 1 mole of an alkylol amine containing at least one reactive hydrogen atom on the amine nitrogen atom. The amides produced according to said patent and which I have found to be suitable for my use are either syrupy liquids or low melting crystalline solids.

Said surfactant is added to photographic coating solutions at the rate of l to 50 grams per kilogram of dry gelatin. It may be the only surfactant in the coating solution or it may be used in combination with others, particularly saponin. Rather strangely, when the aforesaid amides are employed with saponin, they appear to suppress the objectionable characteristics of the saponin.

The following examples will serve to illustrate the invention but it is to be understood that the invention is not restricted thereto.

Example 1 Ten kgs. of gelatin-silver noodles were melted and diluted with 12 liters of water. The gelatin-silver noodles consisted of 0.25 kg. of colloidal silver dispersed in 9.15 kgs. of water containing 0.6 kg. of gelation. To the melted solution were added 2.5 gms. of glyoxal for hardening and 25 gms. of Emcol 5100. This emulsion was brought to a temperature of 40 C. and coated on a cellulose acetate support to a dry coating thickness of 2.0- 2.5 microns. This coating solution was free from foam and froth, and the coated antihalation layer was completely free of repellent spots. Also, it had superior overall uniformity. Another gelatino silver emulsion, simi lar except that gms. of saponin were used instead difilcult to keep the emulsion bubble-free.

Example I! A gelatino silver emulsion was prepared as in Example I but an equivalent amount of N,N'-di-(B-hydroxyethyl)- lauramide was used instead of Emcol 5100. The results were essentially the same.

Example III A gelatino silver emulsion was prepared as in Example I and coated with the aid of 15 gms. of N,N-di(;3- hydroxyethyl)lauramide instead of the 25 gms. of Emcol 5100. Again this layer was superior to that obtained with the aidof saponin. The dried layer was overcoated in the conventional manner with a color emulsion layer sensitized to red light. This emulsion layer contained a cyan color forming agent for subsequent coupling with the developer, as well as 10 gms. of saponin and 10 gms. of Emcol 5100 per kg. of emulsion for spreading. This layer was applied easily without entrapping air bubbles between the two surfaces.

Example IV The procedure is the same as in Example III excepting that the color emulsion layer containing the cyan color former was compounded with 5 gms. of N,N'-di- (B-hydroxyethyl)lauramide in lieu of saponin and Emcol 5100.

Example V To a aqueous solution of an acid processed, pigskin-type gelatin adjusted to pH 6 were added 10 gms. of Emcol 5100, 4 gms. of 40% formaldehyde and 10 gms. of one of the commercially available quaternary ammonium salts that have high fungicidal activity. This melt was heated to 40 C. and coated upon both sides of an 8 ml. thick clear support. The optical clarity and the uniformity of these coatings were such that they could be used for non-fogging viewing windows, as for exam plc, in gas mask lenses.

Example Vl To 10 kgs. of an ammonia-type emulsion containing approximately 1 kg. of silver halide and 950 gms. of gelatin were added 500 mls. of a 5% solution of N-rnonohydroxyethyl-di-palmitylamide. This solution was coated with complete freedom from repellent spots and foam and gave a dried emulsion layer which was extremely uniform. After short but yet adequate development times, the speed and gradient of this film were significantly greater than those of a similar film containing an equal amount of saponin in place of the mcol.

Example VIII To 1 kg. of gelatin dissolved in 50 liters of water was added 1 liter of a 5% solution of Emcol 5100. This solution was coated over a wet chilled gelatino silver halide emulsion layer that had been panchromatically sensitized and coated with the aid of 5 gms. of saponin per 10 kgs. of emulsion. This surface gelatin layer coated uniformly with no tendency to entrap bubbles and, when the film was dry, its coeificient of friction was 0.30 compared to a value of 0.35 for a similar film in which saponin instead of the Emcol 5100 had been'used as the spreading agent for the surface layer. Practical advantage of this coefiicient of friction was better performance of the film in cameras. Also, it is less likely to be abraded when coming in contact with other materials.

Example IX To 1 kg. of gelatin dissolved in 12 liters of water were added 3 gms. of glyoxal and 10 gms. of N,N'-di(,8-hydroxyethyl)lauramide. The pH was adjusted to 5.0 and mls. of a 10% aqueous acid magenta dye solution were added. The antihalation solution presented a very uniform appearance after coating on subbed cellulose acetate film base. It could be coated at 10% faster speed without skipping than a solution similar in composition except that saponin, in an equal amount, was used instead of the alkylolamine fatty acid condensation product.

I claim:

1. A photographic element comprising a support consisting of a single integral film and a uniform layer consisting essentially of a gelatin-colloidal silver suspension containing a surfactant consisting essentially of the amides from the condensation of an aliphatic ethanolamine having at least one reactive hydrogen atom on the nitrogen atom thereof and a fatty acid having from 12 to 22 carbon atoms in direct contact with said film and firmly adhered thereto.

2. The composition as defined in claim 1 wherein the surfactant is N,N-di(p-hydroxyethyl)lauramide.

3. A photographic element comprising a support and a light sensitive silver halide emulsion layer which contains a surfactant obtained by condensing 1 mole of coconut fatty acids with considerably more than 1 mole of diethanolamine to produce an amide.

References Cited in the file of this patent UNITED STATES PATENTS 2,089,212 Kritchevsky Aug. 10, 1937 2,139,778 Slack et al Dec. 13, 1938 2,368,287 Chilton Jan. 30, 1957 2,805,948 Gerhardt Sept. 10, 1957 

1. A PHOTOGRAPHIC ELEMENT COMPRISING A SUPPORT CONSISTING OF A SINGLE INTEGRAL FILM AND A UNIFORM LAYER CONSISTING ESSENTIALLY OF A GELATIN-COLLOIDAL SILVER SUSPENSION CONTAINING A SURFACTANT CONSISTING ESSENTIALLY OF THE AMIDES FROM THE CONDENSATION OF AN ALIPHATIC ETHANOLAMINE HAVING AT LEAST ONE REACTIVE HYDROGEN ATOM ON THE NITROGEN ATOM THEREOF AND A FATTY ACID HAVING FROM 12 TO 22 CARBON ATOMS IN DIRECT CONTACT WITH SAID FILM AND FIRMLY ADHERED THERETO. 